Mossbauer electric field gradient

Figure 4.54 The effect of an electric field gradient (EFG) creating asymmetry in the electron distribution round a gold nucleus, leading to a quadrupole splitting in the Mossbauer spectrum. (Reproduced with permission from Gold Bull., 1982,15, 53, published by World Gold Council.)...

Relativistic effects in core properties like electric field gradients can be extremely large [103]. As the isotope 197-Au is widely used is Mossbauer spectroscopy [104], an... 

In the stochastic theory of lineshape developed by Blume [31], the spectral lines are calculated under the influence of a time-dependent Hamiltonian. The method has been successfully applied to a variety of dynamic effects in Mossbauer spectra. We consider here an adaptation due to Blume and Tjon [32, 33] for a Hamiltonian fluctuating between two states with axially symmetric electric field gradients (efg s), the orientation of which is parallel or perpendicular to each other. The present formulation is applicable for states with the same... 

Spiering, H. The Electric Field Gradient and Quadmpole Interaction. In Long, G. (ed.) Mossbauer Spectroscopy Applied to Inorganic Chemistry, p. 79. Plenum, New York (1984)... 

Table 5.3 Relative peak areas in Mossbauer quadrupole doublets as a function of the angle between the radiation and the electric field gradient. 

Because the interactions measured in Mossbauer experiments are products of atomic and nuclear factors, experiments on iodine isotopes have yielded values of the change of nuclear radius between the ground state and the excited state, AR/R, quadrupole moment values Q, and magnetic moment values, fi, as well as electric field gradients and internal magnetic fields. 

For nuclei possessing an electric quadrupole moment, the electric field gradient at the atomic nuclei can be measured accurately by techniques such as nuclear quadrupole resonance, Mossbauer spectroscopy, nuclear magnetic resonance, and, for gaseous species, by microwave spectroscopy. The diffraction data permit an... 

For a number of nuclei, the electric field gradient at the nucleus can be obtained very accurately from spectroscopic measurements using Mossbauer or magnetic resonance techniques as mentioned in chapter 8. 

Maruthe,V.R. Trautwein, A. (1983) Calculation of charge density, electric field gradient and internal magnetic field using molecular orbital cluster theory. In Thosar, B.V. (ed.) Advances in Mossbauer spectroscopy. Elsevier, Amsterdam, 398-449 Matijevic, E. Cimas S. (1987) Formation of uniform colloidal iron(lll) oxides in ethylene... 

The ion [Au(CN)2] has been subjected to exhaustive theoretical and spectroscopic studies.62,71,85,395-397 In 197Au Mossbauer studies, the sign of the electric field gradient was shown to be negative and the Mossbauer parameters are strongly affected by pressure.62,398-400... 

Mossbauer 107 to 109 Excitation of atomic nuclei Electric-field gradients at the nucleus produced by differences in bond types (Section 27-6)... 

The electric field gradient (axially symmetric for convenience) at the nucleus can be measured using the Mossbauer effect, if... 

The quadrUpole interaction of the quadrupole moment of the I — 3/2 excited isomeric state of 57Fe with an electric field gradient at the nuclear position produces a characteristic line pair in Mossbauer spectra as shown in Fig. 2. The energy difference is called the quadrupole splitting... 

Fig. 2. Mossbauer spectrum resulting from nonzero electric field gradient at the Mossbauer nuclear position for a powder sample...

Abstract. We report the results of experimental and theoretical studies of 13C and 15N shifts in proteins and model systems, together with 57Fe shifts and Mossbauer quadrupole splittings (electric field gradients) in metalloporphyrins and metalloproteins. The ability to relate these spectroscopic observables to structure by using quantum chemical methods opens up new opportunities for predicting and refining protein structure. 

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